Research Of The Gravity Flow Depositions In Lake Basin Of Chang 6 Reservoir In Huangling Area,Ordos Basin

The research object of this paper is Chang 6 oil formation of the Huangling area in Ordosbasin.Based on the previous research results,the thesis applies the theories and methods of sedimentology,stratigraphy and lithofacies palaeogeography.the characteristics of strata,provenance,sedimentary system,gravity flow deposition and its controlling factors were studied systematically by drilling,logging and test analysis.The lake basin that is Yanchang Formation ofHuangling area of Ordos basin of is in the shrinking stage in Chang 6 sedimentary period.In order to clarify the characteristics of the study area,Chang6 reservoirisdividedintothreesmalllayers that is studied.The provenance characteristics of the Chang 6 reservoir in the Huangling area was studied from the different angles,including paleocurrent,the light mineral,the cuttings type and the heavy mineral assemblage.The results show that there are two major provenances in the southwest and northeast of the study area,which are mainly affected by the southwest provenance,and the provenance is abundant.Based on the analysis of lithology signs,structural features,sedimentary structural markers,paleontological markers and logging facies markers,the lacustrine depositional system was identified in the Chang 6 sedimentary period.In addition to the lacustrine facies under normal sedimentation,gravity flow deposits are event deposits developed in the background of semi deep lake deep lake sediments.At this point,combined with the typical sedimentary structure and logging data,it is found that there are three types of gravity flow in the basin: slump,sandy debris flows and turbidite.Theyhavedifferentgeneticmechanismsandsedimentary characteristics.The temporal and spatial evolution of gravity flow deposits are further studied from the vertically,transverse and horizontal directions,and the corresponding sedimentary models are established.Slope is one of the main controlling factors of gravity flow deposition.According to the different slope,the gravity flow deposition is divided into two types.One is called the steep slope gravity flow,because it is affected by the southwest steep slopeand the other is called a gentle slope,which is controlled by the gentle slope of the Northeast.There are significant differences in the gravity flow deposition between the two slopes.Mainly include:(1)Different combinations of sedimentary microfacies.(2)Genetic types and distribution characteristics of sand bodies.(3)Sand body thickness.Based on the study of lithology,physical properties and sand body thickness,further analysis of the Huangling area of sandbody sedimentary microfacies.It is mainly composed of sandy clastic flow sand body and turbidite sand body.The sandy debris flow sand body has the most extensive development scale,the largest sedimentary thickness and the highest exploration value.Because of the best physical property and the largest sand body thickness of Chang 63 oil formation,it is a favorable exploration position.